Yes, gasp away—I'm writing about craft.
Well, sort of.
I'm really writing about the dangers of waxing poetic. You see, I started as a poet, publishing my annoying teenage drivel for years and years before seriously writing anything. Now there are good things about that—it taught me to use words to create bigger effects, for one—and there are horrible evil things about that, the worst of which is pacing my prose with punctuation.
Now, to an extent, this is allowable, such as when your character talks. Like. This. That's a good, widely accepted way to use non-grammatical, artistic, poetic punctuation in prose.
However, there are two things not to ever use for pacing, one of which I am horrendously notorious for: commas and em-dashes.
Now, I blame the standard school system for a lot of the comma issues—they tell you commas are pauses, and they are in poetry. Not in prose. I've seen people inadvertently change the entire meaning of sentences by using commas as pauses, and editors let that slip by, for some reason. Luckily, I don't see it terribly often, but it warrants a mention here.
Now for my big problem—the em-dash. I overuse them for two reasons, the first of which is poetic. It creates more of a pause, better delineates a thought from the surroundings. The other reason, and I believe this holds wider prevalence, is literary analysis. For years, I wrote literary analysis papers, which encourage you to have long, complicated, compound sentences, mixing commas, colons, semi-colons, parentheses, and em-dashes. Of course, being in the public school, no one bothered to properly explain the em-dash.
However, these kinds of errors can be overcome, but they don't die easily. To this very day, if I'm tired or unsure of exactly what I'm writing (i.e. writing by the seat of my pants (the same way I write any and all literary analysis papers)) my em-dashes explode everywhere, and normally they shouldn't be there. It's an ingrained habit but, I still think awareness is the number one thing we can have to make ourselves better writers and more proficient editors.
A good dose of black humor helps, too—makes it much easier to laugh about rejections and the like.